1. Field of the Invention
The present invention relates to improvement of electrical characteristics in a flexure with conductors for a multi-reader which is mounted in a hard disk drive, for example.
2. Description of the Related Art
As hard disk drives increase in capacity while their sizes have been reduced, a further improvement in recording density of a magnetic disk is desired. In order to realize the above, improvement in track density in addition to a liner density of the magnetic disk is desired. However, reducing track width causes a problem of displacement of recording data in the magnetic disk and a reproduction element of a magnetic head.
With respect to this problem, as disclosed in JPH06-215322 A (Patent Literature 1), a method of simultaneously reproducing recording data and a displacement signal and making a correction by providing two reproduction elements (a multi-reader) in a magnetic head has been proposed. Further, as the developed form of the above method, a method of reproducing two-dimensional magnetic recording (TDMR) by a plurality of reproduction elements has been proposed, as disclosed in JP 2011-134372 A (Patent Literature 2). A flexure for mounting a magnetic head comprising a plurality of reproduction elements thereon will be hereinafter referred to as a flexure with conductors for a multi-reader. In the flexure with conductors for a multi-reader, pairs of read traces corresponding to the reproduction elements, respectively, are provided.
The impedance of each pair of read traces should preferably be decreased in order to match the impedance of the read trace pair with that of reproduction elements, etc., and also to reduce power consumption. In an ordinary flexure with conductors comprising a pair of read traces, a window portion is formed by etching on a metal base of an area in which the pair of read traces (the read trace pair) is arranged, thereby adjusting the impedance value. Also in a flexure with conductors for a multi-reader comprising a plurality of read trace pairs, forming a window portion for each of the read trace pair is considered.
However, since the minimum width of a metal base which can be formed by general chemical etching in flexure manufacturing is limited, if an interconnection part continues to be denser and denser as a result of miniaturization of the flexure, it becomes difficult to form an independent window portion in each of the read trace pairs. Hence, in order to reduce the size of the flexure with conductors for a multi-reader, one idea is to form a shared window portion with respect to a plurality of pairs of read trace.
However, if such a window portion is formed, the positional relationship between a positive (a positive phase signal) read trace and a negative (a reverse phase signal) read trace, which constitute a pair of read traces, and the window portion (the external form of a ground) becomes asymmetrical. If the capacitance of the read traces becomes unbalanced between the positive and negative phases, the capability of the read trace pair which removes noise by transmitting a differential signal as a pair is lowered. In this case, the read trace pair is likely to be affected by crosstalk (noise) from a write trace pair.
Up to the present, various technologies for suppressing crosstalk in a pair of read traces which transmit a differential signal have been proposed with respect to an ordinary flexure with conductors for a single reader. Meanwhile, technologies for suppressing crosstalk in pairs of read traces in a flexure with conductors for a multi-reader are barely known. For example, even if a crosstalk suppression technology intended for a flexure with conductors for a single reader as disclosed in JP 2006-48800 A (Patent Literature 3) or JP 2006-331485 A (Patent Literature 4) is applied to a flexure with conductors for a multi-reader, the applied technology will not bring about any advantage or will induce an adverse reaction on the contrary.